busybox-initramfs 1:1.13.3-1ubuntu7 (i386 binary) in ubuntu karmic

BusyBox combines tiny versions of many common UNIX utilities into a single
small executable. It provides minimalist replacements for the most common
utilities you would usually find on your desktop system (i.e., ls, cp, mv,
mount, tar, etc.). The utilities in BusyBox generally have fewer options than
their full-featured GNU cousins; however, the options that are included
provide the expected functionality and behave very much like their GNU
counterparts.
.
busybox-initramfs provides a statically linked simple stand alone shell
that provides only the basic utilities needed for the initramfs.